While even I (*gasp!* really?!?, moi? *heh*) am subject to errors of this sort from time to time (particularly after struggling to read through many long text samples by subliterates), a fairly sure sign of poor literacy (that is, not being well-read) is using compound words that are adjectives or adverbs in place of noun or verb phrases OR using separate words when compounds of those words is proper.
Already vs All ready
Altogether vs All together
Anyone vs Any one
Anything vs Any thing
Awhile vs A while. . .
. . .
Backseat vs Back seat. . .
. . .
Everyday vs Every day. . .
. . .
Maybe vs May be. . .
. . .
Sometime vs Some time. . .
. . .
Workout vs Work out. . .
And many, many more.
Why do some writers regularly mix such things up? Because they are not well-read. Such writers may have read a lot of text, but if they have, the text they have read has been written by poorly-read, less than genuinely literate writers. Being well-read requires having read enough text by genuinely literate writers to have absorbed good language skills, which includes, among many attributes, knowing the useful distinctions between such compound words as listed above and the phrases they’ve been compounded from. (Insert obligatory Winston Churchill comment about ending sentences with prepositions here. 🙂 )
Of course, that’s only one, of many, abilities a literate writer will have in his bag, but when it’s missing, one can be pretty sure that the writer who lacks this ability is just too lazy to have done his homework. He might be a good storyteller or public speaker/lecturer, but he’s not really literate enough to be trusted with a pen (or keyboard) and a publisher (even if it is himself*).
*Subliterate self-pubs/”Indie” writers almost invariably are too cheap (or financially strapped) to pay for decent editing–either content or line editing–and even if they try “crowdsourcing” such things usually only appeal to their own cohort of subliterates to check their work. *gagamaggot* Of course, there are literate “Indie” writers with literate peers and readers, and their works are generally edited to a standard that, nowadays, exceeds that of the increasingly poor quality of editing coming from traditional publishing houses. Not common but welcome.